Apparatus for drilling and enlarging a bore

ABSTRACT

An earth boring method and apparatus in which a dam or the like is first bored through in a substantially horizontal direction by a preboringhead driven by a conventional mechanical driving means, after which the leading preboringhead is dismounted from the preboring or drillstring and an enlarging borehead is connected to the mechanical driving means and slid over the preboringstring and is connected via a second larger boringstring to the mechanical driving means for enlarging the predrilled borehole.

United States Patent [191 Hasewend [451 Oct. 7, 1975 1 1 APPARATUS FOR DRILLING AND ENLARGING A BORE [75] Inventor: Florian Hasewend, Kapfenberg,

Austria [73] Assignee: Gebr. Bohler & Co.

Aktiengesellschaft, Vienna, Austria 22 Filed: Nov. 14, 1973 21 Appl. No.: 415,829

[30] Foreign Application Priority Data [58] Field of Search 175/62, 53, 262, 402, 403, 175/404, 405, 408, 415, 418, 386, 135, 214, 215,171, 207; 166/301; 173/105 [56] References Cited UNITED STATES PATENTS 1,894,446 1/1933 McKenny 175/22 X 2,349,033 5/1944 Elliott Miller et a1. 175/62 X 2,884,227 4/1959 Hjalsten 175/418 X 2,960,312 11/1960 Kandle 175/410 X 3,154,158 10/1964 Lincoln 175/135 3,163,245 12/1964 York 175/410 X 3,217,816 11/1965 Boyer 175/57 3,232,360 2/1966 Dickinson 175/62 3,485,301 12/1969 Stewart 175/407 X 3,507,342 4/1970 Hasewend et al 175/62 3,540,536 11/1970 Huszar 175/215 X 3,640,351 2/1972 Coyne et al 173/105 Primary Examiner-Ernest R. Purser Assistant ExaminerRichard E. Favreau [57] 3 ABSTRACT An earth boring method and apparatus in which a dam or the like is first bored through in a substantially horizontal direction by a preboringhead driven by a conventional mechanical driving means, after which the leading preboringhead is dismounted from the preboring or drillstring and an enlarging borehead is connected to the mechanical driving means and slid over the preboringstring and is connected via a second larger boringstring to the mechanical driving means for enlarging the predrilled borehole.

1 Claim, 3 Drawing Figures U.S. Patent Oct. 7,1975 Shet 2 of2 3,910,361

APPARATUS FOR DRILLING AND ENLARGING A BORE The invention relates to a boring method in which a dam or the like is bored through in a substantially horizontal direction. The aforedescribed boring method is generally carried out by means of a pipe drawstring, on

the lead end of which a borehead is mounted, and which is driven from one end of a darn or the like in a horizontal direction by conventional mechanical driving means. The pipe drawstring, according to the method of the invention, is separated from the driving mechanism and an enlarging borehead ofan increased diameter is slid over the pipe drawstring and thereafter the drawstring is again connected to the mechanical driving means and thereby the hole is bored by means of the enlarging borehead. The invention relates also to an apparatus for carrying out the aforedescribed method.

There is already known a method for boring in earth material, in which a foot path situated between two adjacent ditches can be bored through in a horizontal direction by means of a borestring. After the borestring is separated from' the mechanical driving means, there is slid over the borestring a helically-shaped borehead and by purely rotational boring the borehole is enlarged after the drawstring has been connected to the mechanical driving means.

There are already known hydraulic presses which carry out horizontal or inclined driving of bore or drawstrings into the earth from a shaft, wherein the bore or draw-strings are guided through a press cylinder. A major longitudinal portion of the press is arranged outside of the shaft and for example is supported by means of a casing pipe by the shaft wall.

Both of the aforementioned arrangements make it possible to only carry out the boring operation in soft material, such as earth material and they are not suitable to also carry out a boring operation in loosely or densely compacted rocky soil material.

In another known arrangement for producing substantially horizontal boreholes in rocky or earth material there is only provided a percussion borecrown on the leading end of the borestring and such an arrangement does not permit production of boreholes of large diameter in a simple economical manner.

Furthermore, a process for producing bore-holes for anchoring a member therein is known. In this known process the borestring is introduced into the soil by means of a purely rotational boring operation or by means of a percussion boring operation. Thereafter, the to be anchored pipe-shaped member is introduced through the borepipe in the ground. This process is also not suitable to produce boreholes of relatively large diameter in a simple and economical manner.

It is an object of this invention to provide a process wherein the aforedescribed drawbacks are eliminated, that is to produce boreholes in a simple and economical manner in loose as well as rocky soil in a substantially horizontal direction with relatively large diameter. This is accomplished by means of the boring process of the invention by having the percussion borecrown which is formed as a preboringhead mounted on the preboringstrings to carry out a preboring operation and for carrying out the final boring operation there is also used a percussion borecrown formed as an enlarging borehead which is not only rotated but also percussed.

Hereafter there is described a process in accordance with the invention in conjunction with a drawing in which there is illustrated schematically an arrangement for carrying outthe process.

IN THE DRAWINGS FIG. 1 is viewed partly in section partly in elevation showing the aforementioned arrangement wherein the preboringhead is formed as a percussion borecrown;

FIG. 2 is a partial side view of the same arrangement illustrated in FIG. 1, wherein the final borehead is shown in longitudinal cross section and is embodied as a percussion borecrown which is formed as an enlarging boring-head;

FIG. 3 is a side view of the enlarging boringhead of FIG. 2 illustrated in a larger scale. I 1

Referring now to the drawings, the predrillstring is formed by a plurality of pipe sections 1 threadably connected to each other. This preboring or drillstring is connected to conventional rotary mechanical driving means 5 via an ejection bell 6. The rotary mechanical driving means 5 form part of a percussion boring machine 4 of a known type and this percussion boring machine 4 carries out a substantial horizontal boring operation by means of the preboringstrin'g. The bore material or detritus travels through the ring-shaped leading borehead 2 as well as the pipe sections 1 in the direction of the ejection bell 6 which is provided with laterally disposed openings 7 to which the bored material or detritus is ejected. As soon as the leading borehead 2 has bored through the darn the borehead 2 and the ejection bell 6 are removed from the borestring. Furthermore, the ejection bell 6 is also disconnected from the rotary mechanical driving means 5 of the percussion boremachine 4. Thereafter, there is slid onto the borestring a ring-shaped borehead ll of substantially larger diameter than the preboringhead 2 over the end of the borestring facing the percussion machine 4. A second ejection bell 8, of larger diameter than the previously mentioned ejection bell 6, is threadably connected with the percussion boremachine 4 and is threadably connected to the pipe section 10 of the borehead 11. As can be noted from FIG. 2 the internal diameter of the pipe section 10 is larger than the external diameter of the boringstring which is formed by the pipe section 1. The borehole which has been prebored by the boringstring is now enlarged by the borehead 11, whereby there can be added between the ejection bell 8 and the pipe section 10, in known manner, additional pipe sections 10. The preboringstring and preborehead 2 as well as the pipe section 10 which form the enlarging borestring and the borehead 11 are rotated by means of the mechanical rotary means 5 of the percussion bore machine 4 when the respective pipe strings are connected to the percussion bore machine 4 via the ejection bells 6 or 8. The boringhead 11 has substantially cylindrical collar 12 which is provided with cutting members 13, made of hard metal. A concentric, also substantially cylindrical inner collar 14, is also provided with cutting members 15, made of hard metal. These two collars l2 and 14 are connected to each other by means of a plurality, for example, two preferably radially arranged flanges 16. The bored material or detritus can traverse the borehead 11 as well as the enlarging borestring in an axial direction and exit through the lateral openings 9 in the ejection bell 8. Cylindrical hard metal rods 17 are inserted in the front face of the flanges 16 of the borehead ll of the borecrown body. The advance or retraction of the corresponding borestring is carried out by means of a borecarriage 3 onto which the percussion boremachine 4 is mounted. After the borehead 11 has exited from the side of the dam facing away from the percussion boremachine 4 the preboring string can be pulled out of the enlarging borestring in one unit and there can be introduced in a known manner a supply conduit, for example, a plastic pipe, into the borehole.

- It is possible, in accordance with the process of this invention, to produce even larger boreholes, if one enlarges even further, in accordance with the aforedescribed process, the corresponding borehole with an additional enlarging borehead which has a larger diameter than the previously mentioned borehead 11.

The aforedescribed method has the advantage, when compared to the methods of the prior art that it makes it possible to produce in a simple and economical manner in loose as well as rocky soil a substantially horizontal borehole with a relatively large diameter.

of the appended claims. What is claimed is: 1. An earth boring apparatus for drilling a substantially horizontal borehole in a darn or the like, comprising in combination, a first pipestring, a first bore-head removably connected to the leading end of said first pipestring, a second pipestring having an interior diameter which is larger than the interior diameter of said first pipestring, a second borehead removably mounted on the leading end of said second pipestring, said first and second borehead being formed as percussion borecrowns, a percussion driving machine, first and second ejection bell members adapted to operatively connect the percussion driving machine respectively to said first and second pipestrings, said second pipestring having an interior diameter which is larger than the exterior diameter of said first pipestring; said second borehead has a substantially first cylindrical collar bit portion and a second inner substantially cylindrical collar bit portion, at least two substantially radially extending flange members connecting said first and second collar bit portions, said first and second collar bit portions having cutting members made of hard metal and said flange portion having cutting rods made of hard metal.

l l l 

1. An earth boring apparatus for drilling a substantially horizontal borehole in a dam or the like, comprising in combination, a first pipestring, a first bore-head removably connected to the leading end of said first pipestring, a second pipestring having an interior diameter which is larger than the interior diameter of said first pipestring, a second borehead removably mounted on the leading end of said second pipestring, said first and second borehead being formed as percussion borecrowns, a percussion driving machine, first and second ejection bell members adapted to operatively connect the percussion driving machine respectively to said first and second pipestrings, said second pipestring having an interior diameter which is larger than the exterior diameter of said first pipestring; said second borehead has a substantially first cylindrical collar bit portion and a second inner substantially cylindrical collar bit portion, at least two substantially radially extending flange members connecting said first and second collar bit portions, said first and second collar bit portions having cutting members made of hard metal and said flange portion having cutting rods made of hard metal. 